BIOL 2311 Electron Transport Chain Steps

For Exam 3 (and Quiz 5)

1

Complex I picks up high energy e- from NADH and conducts them via electron carriers.

2

Complex II oxidizes FADH2 to FAD, two electrons released are transferred to ubiquinone, and released protons go into the matrix.

3

Complex III accepts electrons from ubiquinone and transfers them through the electron carriers in the complex.

4

Complex IV accepts e- from cytochrome c and delivers them via e- carriers to oxygen.

5

e- release free energy. Some lost as heat, some used by mitochondrion to transport H+ across inner mitochondrial membrane from matrix to intermembrane compartment at I, III, and IV. 

6

Resulting H+ gradient supplies ATP synthase energy for ATP synthesis.

7

H+ flows across inner membrane and into matrix through ATP synthase channel.

8

Flow of H+ activates ATP synthase, making headpiece and stalk rotate.

9

Headpiece catalyzes synthesis of ATP from ADP and Pi.